Proton conducting membrane and process for producing the same

ABSTRACT

A proton conductive membrane displays sufficient proton conductivity even at low humidities and low temperatures. 
     The proton conductive membrane includes:
         a block copolymer including an ion conductive polymer segment (A) and an ion nonconductive polymer segment (B), the segment (A) and the segment (B) being covalently bound in a manner such that main chain skeletons of the segments are covalently bound at aromatic rings thereof through binding groups,   (i) the membrane having a morphology including a microphase separated structure,   (ii) the ion conductive polymer segment (A) forming a continuous phase.

FIELD OF THE INVENTION

The present invention relates to a proton conductive membrane suitablefor use as electrolytes in solid polymer fuel cells. More particularly,the invention concerns a proton conductive membrane suitable aselectrolytes in hydrogen powered fuel cells for vehicles, and a processfor producing the same.

BACKGROUND ART

A fuel cell essentially consists of two catalyst electrodes and a solidelectrolyte membrane sandwiched between the electrodes. Hydrogen, thefuel, is ionized at one of the electrodes, and the hydrogen ions diffusethrough the solid electrolyte membrane and combine with oxygen at theother electrode. When the two electrodes are connected through anexternal circuit, an electric current flows and electric power issupplied to the external circuit. Here, the solid electrolyte membranehas functions to diffuse the hydrogen ions, as well as to physicallyisolate the fuel gas (hydrogen) and oxygen and to block the flow ofelectrons.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

It is accepted that the solid electrolyte membranes diffuse hydrogenions through water clusters in hydrophilic channels (ion conductingchannels). Therefore, the ion conductivity drastically lowers at lowhumidities by drying of water and at low temperatures by freezing ofwater.

The quantity of water adsorbed and bound to ion conductive groups in themembrane and the channel structure formed by the ion conductive groupsare considered very important for the ion conductivity.

Block copolymers in which two or more incompatible polymers (blockchains) are covalently bound into one polymer chain permit nanometerscale control of arrangement of the chemically different components. Inblock copolymers, chemically different block chains repel each other toproduce short-range interaction which causes the block chains to beseparated into respective phases (microdomains). When the block chainsare covalently bound, long-range interaction is produced to arrange themicrodomains in certain order. The microdomains of block chains gatherto make a structure called the microphase separated structure.

Ion conductive membranes of block copolymers are generally fabricated byspreading absolution of the block copolymer in an organic solvent on anappropriate substrate and removing the solvent. The microphase separatedstructures in the membranes are crystalline structures such as sphericalmicelle structure, cylindrical structure and lamella structure dependingon the composition of constituent components and atmosphere, asdisclosed in Annu. Res. Phys. Chem. 1990 (41) 525 (Bates F. S. andFredrickson G. H.) (Nonpatent Document 1). When the microphase separatedstructure is controlled by the composition of constituent components,membrane properties are greatly influenced not only by factors of thephase separated structure but by changes of the constituent components.

-   Nonpatent Document 1: Annu. Res. Phys. Chem. 1990 (41) 525    (Bates F. S. and Fredrickson G. H.)

Means for Solving the Problems

The present inventors studied in view of the above problems in thebackground art and have arrived at a solid polymer electrolyte membranethat comprises a block copolymer comprising an ion conductive polymersegment (A) and an ion nonconductive polymer segment (B), the segment(A) and the segment (B) being covalently bound in a manner such thatmain chain skeletons making up the copolymer are covalently bound ataromatic rings thereof through binding groups, wherein (i) the membranehas a morphology including a microphase separated structure and (ii) thesegment (A) forms a continuous phase, whereby ion conductive groups arearranged through the membrane and can adsorb and bind thereto increasedamounts of water, and consequently water is prevented from drying at lowhumidities and from freezing at low temperatures and the membrane canachieve sufficient proton conductivity even at low humidities and lowtemperatures.

The present inventors have also found that in fabricating the protonconductive membrane, an organic solvent that is not interactive with theion conductive polymer segment (A) may be used as a casting solvent fordissolving the copolymer, whereby the spatial arrangement of the ionconductive groups in the membrane can be easily controlled and the ionconductive polymer segment (A) forms a continuous phase in the solidpolymer electrolyte membrane. The present invention has been completedbased on the findings.

The proton conductive membrane and production thereof according to thepresent invention are as follows.

(1) A proton conductive membrane comprising:

a block copolymer comprising an ion conductive polymer segment (A) andan ion nonconductive polymer segment (B), the segment (A) and thesegment (B) being covalently bound in a manner such that main chainskeletons of the segments are covalently bound at aromatic rings thereofthrough binding groups,

(i) the membrane having a morphology including a microphase separatedstructure,

(ii) the ion conductive polymer segment (A) forming a continuous phase.

(2) The block copolymer includes the polymer segments (A) and (B) thatcomprise repeating structural units represented by Formulae (A) and (B),respectively:

wherein Y is a divalent electron-withdrawing group; Z is a divalentelectron-donating group or a direct bond; Ar is an aromatic group havinga substituent —SO₃H; m is an integer ranging from 0 to 10; n is aninteger ranging from 0 to 10; and k is an integer ranging from 1 to 4;

wherein A and D are each a direct bond or at least one structureselected from the group consisting of —Co—, —SO₂—, —SO—, —CONH—, —COO—,—(CF₂)₁— (where 1 is an integer ranging from 1 to 10), —(CH₂)₁— (where 1is an integer ranging from 1 to 10), —C(R′)₂— (where R′ is an alkylgroup, a fluoroalkyl group or an aryl group), —O—, —S—, cyclohexylidenegroup and fluorenylidene group; B's are each an oxygen or a sulfur atom;R¹ to R¹⁶ are the same or different from one another and are each atleast one atom or group selected from the group consisting of a hydrogenatom, a fluorine atom, alkyl groups, partially or fully halogenatedalkyl groups, allyl groups, aryl groups, nitro group and nitrile group;s and t are the same or different and are each an integer ranging from 0to 4; and r is an integer of 0 or 1 or greater.

(3) The ion conductive polymer segment has a sulfonic acid group.

(4) A process for producing the above proton conductive membrane,comprising dissolving a block copolymer in a casting solvent, the blockcopolymer comprising an ion conductive polymer segment (A) and an ionnonconductive polymer segment (B) that are covalently bound to eachother, casting the solution over a substrate, and drying,

the casting solvent containing at least 30% by weight of an organicsolvent that is not interactive with the ion conductive polymer segment(A).

(5) The process for producing the proton conductive membrane asdescribed above, wherein the organic solvent that is not interactivewith the ion conductive polymer segment (A) (i) does not contain anitrogen-containing substituent in which the nitrogen atom is bonded bya single bond or a double bond, and (ii) contains at least one groupselected from the group consisting of —O—, —OH, —CO—, —SO₂—, —SO₃—, —CNand —COOR (where R is a hydrogen atom, a hydrocarbon group or a salt).

Effect of the Invention

The proton conductive membrane according to the present invention canachieve sufficient proton conductivity even at low humidities and lowtemperatures.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic sectional view showing a morphology of an ionconductive membrane fabricated in Example 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The proton conductive membrane and production thereof according to thepresent invention will be described in detail hereinbelow.

(Morphology)

The proton conductive membrane of the invention comprises a blockcopolymer comprising an ion conductive polymer segment (A) and an ionnonconductive polymer segment (B) that are covalently bound in a mannersuch that main chain skeletons of the polymer segments are covalentlybound at aromatic rings thereof through binding groups, and

(i) the membrane has a morphology including a microphase separatedstructure, and

(ii) the ion conductive polymer segment (A) forms a continuous phase.The copolymer will be described later.

The microphase separated structures are crystalline structures such asspherical micelle structure, cylindrical structure and lamella structuredepending on the composition of constituent components and atmosphere,as disclosed in Annu. Res. Phys. Chem. 1990 (41) 525 (Bates F. S. andFredrickson G. H.) (Nonpatent Document 1). The microphase separatedstructures are identified by TEM observation. Such microphase separatedstructures are unstable to heat and easily change into other microphaseseparated structures when exposed to temperatures not less than theglass transition temperature of the block copolymer.

The ion conductive polymer segment (A) preferably forms an isotropiccontinuous phase. Also preferably, the ion nonconductive polymer segment(B) forms a non-continuous phase, more preferably a structure similar toa dispersed phase. The long period of the structure is preferably in therange of 1 nm to 200 nm, more preferably 1 nm to 100 nm.

When the ion conductive polymer segment (A) forms a continuous phase,ion conductive groups in the segment (A) are arranged uniformly throughthe membrane and can adsorb and bind thereto increased amounts of water.Consequently, water is prevented from drying at low humidities and fromfreezing at low temperatures and the proton conductive membrane canachieve sufficient proton conductivity even at low humidities and lowtemperatures.

If the ion conductive polymer segment (A) forms a non-continuous phase,the ion conductive groups in the segment (A) are not arranged uniformlythrough the membrane and allow reduced amounts of water to be adsorbedand bound thereto. Consequently, the proton conductive membrane oftenfails to achieve sufficient proton conductivity at low humidities andlow temperatures.

The continuous phases are confirmed by TEM observation.

Examples of the ion conductive groups in the polymer segment (A) includesulfonic acid group, carboxyl group and phosphoric acid group. Of theseion conductive groups, the present invention preferably employs thesulfonic acid group, in which case the membrane can achieve very highproton conductivity.

The proton conductive membrane which has a microphase separatedstructure and in which the ion conductive polymer segment (A) forms acontinuous phase is suitable for use in hydrogen fuel cells for thereasons that the ion conductive groups in the segment (A) are arrangeduniformly through the membrane and can adsorb and bind thereto increasedamounts of water, and consequently water is prevented from drying at lowhumidities and from freezing at low temperatures and the membrane canachieve sufficient proton conductivity even at low humidities and lowtemperatures. Furthermore, the membrane can be reduced in size andweight and is therefore suited for use in vehicle fuel cells.

The block copolymer used in the present invention includes repeatingstructural units represented by Formulae (A) and (B) which will be givenbelow. Preferably, the copolymer is a block copolymer (polyarylenehaving a sulfonic acid group) represented by Formula (C) which will begiven below. The use of the copolymer represented by Formula (C) leadsto increased water resistance and mechanical strength, and also higherion exchange capacity. Consequently, the ion conductive groups in thesegment (A) can adsorb and bind thereto increased amounts of water, andthe proton conductivity is enhanced.

(Polyarylene Having a Sulfonic Acid Group)

The polyarylene having a sulfonic acid group will be described indetail.

The polyarylene having a sulfonic acid group includes repeatingstructural units represented by Formulae (A) and (B) below, and is apolymer, preferably a block copolymer, represented by Formula (C) below.

In the above formula, Y is a divalent electron-withdrawing group such as—CO—, —SO₂—, —SO—, —CONH—, —COO—, —(CF₂)₁— (where 1 is an integer offrom 1 to 10) and —C(CF₃)₂—; and

Z is a direct bond or a divalent electron-donating group such as—(CH₂)—, —C(CH₃)₂—, —O—, —S—, —CH═CH—, —C≡C— and groups represented by:

The electron-withdrawing group is defined as having a Hammettsubstituent constant of not less than 0.06 at the m-position of thephenyl group and not less than 0.01 at the p-position.

Ar denotes an aromatic group with a substituent —SO₃H. Exemplaryaromatic groups include phenyl, naphthyl, anthracenyl and phenanthylgroups, with phenyl and naphthyl groups being preferred.

In the formula, m is an integer of from 0 to 10, preferably from 0 to 2;n is an integer of from 0 to 10, preferably from 0 to 2; and k is aninteger of from 1 to 4.

In Formula (B), A and D are the same or different and are each a directbond or at least one structure selected from the group consisting of—CO—, —SO₂—, —SO—, —CONH—, —COO—, —(CF₂)₁— (where 1 is an integerranging from 1 to 10), —(CH₂)₁— (where 1 is an integer ranging from 1 to10), —C(R′)₂— (where R′ is an alkyl group, a fluoroalkyl group or anaryl group), —O—, —S—, cyclohexylidene group and fluorenylidene group.Examples of R′ in the structure —C(R′)₂— include alkyl groups such asmethyl, ethyl and propyl groups, fluoroalkyl groups such astrifluoromethyl and heptafluoroethyl groups, and aryl groups such asphenyl and naphthyl groups. Specific examples of the structures —C(R′)₂—include —C(CF₃)₂—, —C(CH₃)₂— and —C(C₆H₅)₂—

Of the above structures, direct bond, —CO—, —SO₂—, —C(R′)₂— (where R′ isan alkyl, fluoroalkyl or aryl group), —O—, cyclohexylidene group andfluorenylidene group are preferred.

B's are each an oxygen or a sulfur atom, preferably an oxygen atom.

R¹ to R¹⁶ are the same or different from one another and are each atleast one atom or group selected from the group consisting of a hydrogenatom, a fluorine atom, alkyl groups, partially or fully halogenatedalkyl groups, allyl groups, aryl groups, nitro group and nitrile group.

The alkyl groups include methyl, ethyl, propyl, butyl, amyl, hexyl,cyclohexyl and octyl groups. The halogenated alkyl groups includetrifluoromethyl, pentafluoroethyl, perfluoropropyl, perfluorobutyl,perfluoropentyl and perfluorohexyl groups. The allyl groups includepropenyl group. The aryl groups include phenyl and pentafluorophenylgroups.

The letters s and t are each an integer ranging from 0 to 4. The letterr is an integer of 0 or 1 or greater generally up to 100, preferably inthe range of 1 to 80.

Preferred examples of the structural units with combinations of s, t, A,B, D and R¹ to R¹⁶ include:

(1) structural units in which s is 1; t is 1; A is —C(R′)₂— (where R′ isan alkyl, fluoroalkyl or aryl group), cyclohexylidene group orfluorenylidene group; B is an oxygen atom; D is —CO— or —SO₂—; and R¹ toR¹⁶ are each a hydrogen atom or a fluorine atom;

(2) structural units in which s is 1; t is 0; B is an oxygen atom; D is—CO— or —SO₂—; and R¹ to R¹⁶ are each a hydrogen atom or a fluorineatom; and

(3) structural units in which s is 0; t is 1; A is —C(R′)₂— (where R′ isan alkyl, fluoroalkyl or aryl group), cyclohexylidene group orfluorenylidene group; B is an oxygen atom; and R¹ to R¹⁶ are each ahydrogen atom, a fluorine atom or a nitrile group.

Specifically, the polyarylene having a sulfonic acid group is a polymerrepresented by Formula (C) below:

wherein A, B, D, Y, Z, Ar, k, m, n, r, s, t and R¹ to R¹⁵ are the sameas A, B, D, Y, Z, Ar, k, m, n, r, s, t and R¹ to R¹⁶ in Formulae (A) and(B), and x and y each indicate a molar proportion of which the total x+yis 100 mol %.

The polyarylene having a sulfonic acid group contains 0.5 to 100 mol %,preferably 10 to 99.999 mol % the repeating structural units of Formula(A) (namely, the units “x”), and 99.5 to 0 mol %, preferably 90 to 0.001mol % the repeating structural units of Formula (B) (namely, the units“y”).

When the polyarylene includes the structural units (A) and (B) in theabove amounts, it has superior water resistance and mechanical strength,and high ion exchange capacity. Consequently, the ion conductive groupsin the segment (A) can adsorb and bind thereto increased amounts ofwater, and the proton conductive membrane shows higher protonconductivity.

The polyarylene may contain structural units other than theaforementioned.

(Production of polyarylene Having Sulfonic Acid Group)

The polyarylene having a sulfonic acid group may be synthesized bycopolymerizing a monomer which has a sulfonate group and is capable offorming the structural units of Formula (A) with an oligomer capable offorming the structural units of Formula (B) to produce a polyarylenehaving a sulfonate group, and hydrolyzing the polyarylene to convert thesulfonate group into the sulfonic acid group.

Alternatively, a polyarylene is previously synthesized which includesstructural units with a skeleton represented by Formula (A) except thatthe structural units have no sulfonic acid or sulfonate groups, and thestructural units represented by Formula (B); and the polyarylene issulfonated to synthesize the polyarylene having a sulfonic acid group.

For convenience of reference, the monomers capable of forming thestructural units of Formula (A) will be referred to as monomers (D)represented by, for example, Formula (D) below; and the oligomerscapable of forming the structural units of Formula (B) will be referredto as oligomers (E) represented by, for example, Formula (E) below.These monomers and oligomers are copolymerized to synthesize thepolyarylene having a sulfonate group. Examples of the monomers (D)include sulfonates represented by Formula (D) below:

In Formula (D), X denotes a halogen atom other than fluorine (i.e.,chlorine, bromine or iodine) or a —OSO₂Z group (where Z is an alkyl,fluorine-substituted alkyl or aryl group); and Y, Z, Ar, m, n and k areas described in Formula (A). R^(a) denotes a hydrocarbon group of 1 to20, preferably 4 to 20 carbon atoms. Specific examples thereof includelinear hydrocarbon groups, branched hydrocarbon groups, alicyclichydrocarbon groups and 5-membered heterocyclic hydrocarbon groups, suchas methyl, ethyl, n-propyl, iso-propyl, tert-butyl, iso-butyl, n-butyl,sec-butyl, neopentyl, cyclopentyl, hexyl, cyclohexyl, cyclopentylmethyl,cyclohexylmethyl, adamantyl, adamantanemethyl, 2-ethylhexyl,bicyclo[2.2.1]heptyl, bicyclo[2.2.1]heptylmethyl, tetrahydrofurfuryl,2-methylbutyl, 3,3-dimethyl-2,4-dioxolanemethyl, cyclohexylmethyl,adamantylmethyl and bicyclo[2.2.1]heptylmethyl groups. Of these,n-butyl, neopentyl, tetrahydrofurfuryl, cyclopentyl, cyclohexyl,cyclohexylmethyl, adamantylmethyl and bicyclo[2.2.1]heptylmethyl groupsare preferred, and neopentyl group is particularly preferable. Ardenotes an aromatic group with a substituent —SO₃R^(b). Exemplaryaromatic groups include phenyl, naphthyl, anthracenyl and phenanthylgroups, with phenyl and naphthyl groups being preferred.

The aromatic group is substituted with one or two or more substituents—SO₃R^(b). When two or more substituents SO₃R^(b) are present, they maybe the same as or different from one another.

R^(b) denotes a hydrocarbon group of 1 to 20, preferably 4 to 20 carbonatoms. Specific examples thereof include the above-described hydrocarbongroups having 1 to 20 carbon atoms. Of such groups, n-butyl, neopentyl,tetrahydrofurfuryl, cyclopentyl, cyclohexyl, cyclohexylmethyl,adamantylmethyl and bicyclo[2.2.1]heptylmethyl groups are preferred, andneopentyl group is particularly preferable.

In the formula, m is an integer of from 0 to 10, preferably from 0 to 2;n is an integer of from 0 to 10, preferably from 0 to 2; and k is aninteger of from 1 to 4.

Specific examples of the sulfonates represented by Formula (D) includethe following compounds:

Also employable are aromatic sulfonate derivatives derived from thecompounds of Formula (D), in which the chlorine atoms are replaced bybromine atoms, in which —CO— is replaced by —SO₂—, and in which thechlorine atoms are replaced by bromine atoms and —CO— is replaced by—SO₂—.

The R^(b) group in Formula (D) is preferably derived from a primaryalcohol, and the β carbon atom is preferably tertiary or quaternary.More preferably, such ester group is derived from a primary alcohol andthe β carbon atom is quaternary. When these two conditions aresatisfied, excellent stability may be obtained during polymerization andno inhibited polymerization or crosslinking will result from theformation of sulfonic acids by deesterification.

The compounds having a skeleton similar to that of the monomers (D) ofFormula (D) except that the compounds have no sulfonic acid or sulfonategroups include the following compounds:

Also Employable are derivatives of the above compounds in which thechlorine atoms are replaced by bromine atoms, in which —CO— is replacedby —SO₂—, and in which the chlorine atoms are replaced by bromine atomsand —CO— is replaced by —SO₂—.

Examples of the oligomers (E) include compounds represented by Formula(E) below:

In Formula (E), R′ and R″ are the same or different and are each ahalogen atom other than fluorine or a —OSO₂Z group (where Z is an alkyl,fluorine-substituted alkyl or aryl group) Indicated by Z, the alkylgroups include methyl and ethyl groups, the fluorine-substituted alkylgroups include trifluoromethyl group, and the aryl groups include phenyland p-tolyl groups.

In Formula (E), A and D are each a direct bond or at least one structureselected from the group consisting of —CO—, —SO₂—, —SO—, —CONH—, —COO—,—(CF₂)₁— (where 1 is an integer ranging from 1 to 10), —(CH₂)₁— (where 1is an integer ranging from 1 to 10), —C(R′)₂— (where R′ is an alkylgroup, a fluoroalkyl group or an aryl group), —O—, —S—, cyclohexylidenegroup and fluorenylidene group.

Examples of R′ in the structure —C(R′)₂— include alkyl groups such asmethyl, ethyl and propyl groups, fluoroalkyl groups such astrifluoromethyl and heptafluoroethyl groups, and aryl groups such asphenyl and naphthyl groups. Specific examples of the structures —C(R′)₂—include —C(CF₃)₂—, —C(CH₃)₂— and —C(C₆H₅)₂—.

In particular, direct bond, —Co—, —SO₂—, —C(R′)₂— (where R′ is an alkyl,fluoroalkyl or aryl group), —O—, cyclohexylidene group andfluorenylidene group are preferred.

B's are each an oxygen or a sulfur atom, preferably an oxygen atom.

R¹ to R¹⁶ are the same or different from one another and are each atleast one atom or group selected from the group consisting of a hydrogenatom, a fluorine atom, alkyl groups, partially or fully halogenatedalkyl groups, allyl groups, aryl groups, nitro group and nitrile group.

The alkyl groups include methyl, ethyl, propyl, butyl, amyl, hexyl,cyclohexyl and octyl groups. The halogenated alkyl groups includetrifluoromethyl, pentafluoroethyl, perfluoropropyl, perfluorobutyl,perfluoropentyl and perfluorohexyl groups. The allyl groups includepropenyl group. The aryl groups include phenyl and pentafluorophenylgroups.

The letters s and t are each an integer ranging from 0 to 4. The letterr is an integer of 0 or 1 or greater generally up to 100, preferably inthe range of 1 to 80.

Preferred examples of the compounds with combinations of s, t, A, B, Dand R¹ to R¹⁶ include:

(1) compounds in which s is 1; t is 1; A is —C(R′)₂— (where R′ is analkyl, fluoroalkyl or aryl group), cyclohexylidene group orfluorenylidene group; B is an oxygen atom; D is —CO— or —SO₂—; and R¹ toR¹⁶ are each a hydrogen atom or a fluorine atom;

(2) compounds in which s is 1; t is 0; B is an oxygen atom; D is —CO— or—SO₂—; and R¹ to R¹⁶ are each a hydrogen atom or a fluorine atom; and

(3) compounds in which s is 0; t is 1; A is —C(R′)₂— (where R¹ is analkyl, fluoroalkyl or aryl group), cyclohexylidene group orfluorenylidene group; B is an oxygen atom; and R¹ to R¹⁶ are each ahydrogen atom, a fluorine atom or a nitrile group.

Specific examples of the compounds having Formula (E) in which r is 0include 4,4′-dichlorobenzophenone, 4,4′-dichlorobenzanilide,bis(chlorophenyl)difluoromethane,2,2-bis(4-chlorophenyl)hexafluoropropane, 4-chlorobenzoicacid-4-chlorophenyl, bis(4-chlorophenyl)sulfoxide,bis(4-chlorophenyl)sulfone, 2,6-dichlorobenzonitrile,9,9-bis(4-hydroxyphenyl)fluorene, derivatives of these compounds inwhich the chlorine atom is replaced by a bromine or an iodine atom, andderivatives of these compounds in which at least one of the halogenatoms substituted at the 4-position is substituted at the 3-position.

Specific examples of the compounds having Formula (E) in which r is 1include 4,4′-bis(4-chlorobenzoyl)diphenyl ether,4,4′-bis(4-chlorobenzoylamino)diphenyl ether,4,4′-bis(4-chlorophenylsulfonyl)diphenyl ether,4,4′-bis(4-chlorophenyl)diphenyl ether dicarboxylate,4,4′-bis[(4-chlorophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenyl ether,4,4′-bis[(4-chlorophenyl)tetrafluoroethyl]diphenyl ether, derivatives ofthese compounds in which the chlorine atom is replaced by a bromine oran iodine atom, derivatives of these compounds in which the halogensubstitution occurs at the 3-position in place of the 4-position, andderivatives of these compounds in which at least one of the substituentsat the 4-position in the diphenyl ether is substituted at the3-position.

The compounds having Formula (E) further include2,2-bis[4-{4-(4-chlorobenzoyl)phenoxy}phenyl]-1,1,1,3,3,3-hexafluoropropane,bis[4-{4-(4-chlorobenzoyl)phenoxy}phenyl]sulfone, and compoundsrepresented by the following formulae:

For example, the compounds represented by Formula (E) may be synthesizedby the following process.

First, the bisphenols combined together by the electron-withdrawinggroups are converted into an alkali metal salt of correspondingbisphenol by addition of an alkali metal such as lithium, sodium orpotassium, or an alkali metal compound such as an alkali metal hydride,an alkali metal hydroxide or an alkali metal carbonate, in a polarsolvent of high dielectric constant such as N-methyl-2-pyrrolidone,N,N-dimethylacetamide, sulfolane, diphenyl sulfone or dimethylsulfoxide.

The alkali metal is generally used in slight excess over the hydroxylgroups of the bisphenol, for example 1.1 to 2 times, preferably 1.2 to1.5 times the equivalent weight of the hydroxyl groups. Thereafter, thealkali metal salt of bisphenol is reacted with a halogen-substituted,e.g., fluorine- or chlorine-substituted, aromatic dihalide compoundwhich has been activated by the electron-withdrawing groups, in thepresence of a solvent that can form an azeotropic mixture with water,such as benzene, toluene, xylene, hexane, cyclohexane, octane,chlorobenzene, dioxane, tetrahydrofuran, anisole or phenetole. Examplesof the aromatic dihalide compounds include 4,4′-difluorobenzophenone,4,4′-dichlorobenzophenone, 4,4′-chlorofluorobenzophenone,bis(4-chlorophenyl)sulfone, bis(4-fluorophenyl)sulfone,4-fluorophenyl-4′-chlorophenylsulfone,bis(3-nitro-4-chlorophenyl)sulfone, 2,6-dichlorobenzonitrile,2,6-difluorobenzonitrile, hexafluorobenzene, decafluorobiphenyl,2,5-difluorobenzophenone and 1,3-bis(4-chlorobenzoyl)benzene. From theviewpoint of reactivity, the aromatic dihalide compound is preferably afluorine compound. But taking the subsequent aromatic coupling reactioninto account, the aromatic nucleophilic substitution reaction should bedesigned to take place so as to yield a molecule having a chlorine atomat its end(s). The active aromatic dihalide compound may be used in anamount 2 to 4 times, preferably 2.2 to 2.8 times the moles of thebisphenol. The bisphenol may be formed into an alkali metal salt ofbisphenol prior to the aromatic nucleophilic substitution reaction. Thereaction temperature is in the range of 60 to 300° C., preferably 80 to250° C. The reaction time ranges from 15 minutes to 100 hours,preferably from 1 to 24 hours. Optimally, the active aromatic dihalidecompound is a chlorofluoro compound as shown in the formula below thathas two halogen atoms different in reactivity from each other. The useof this compound is advantageous in that the fluorine atompreferentially undergoes the nucleophilic substitution reaction withphenoxide so that the objective chlorine-terminated active compound maybe obtained.

wherein A is as defined in Formula (E).

Alternatively, the nucleophilic substitution reaction may be carried outin combination with electrophilic substitution reaction to synthesize anobjective flexible compound including the electron-withdrawing andelectron-donating groups, as described in JP-A-H02-159.

Specifically, the aromatic bis-halide activated by theelectron-withdrawing groups, such as bis(4-chlorophenyl)sulfone, issubjected to the nucleophilic substitution reaction with a phenol;thereafter the resultant bis-phenoxy compound is subjected toFriedel-Crafts reaction with, for example, 4-chlorobenzoyl chloride togive an objective compound. Examples of the aromatic bis-halidesactivated by the electron-withdrawing groups include the compoundsdescribed above. The phenol compound may be substituted, but ispreferably unsubstituted from the viewpoints of heat resistance andflexibility. When substituted, the substituted phenol compound ispreferably an alkali metal salt. Any of the alkali metal compoundsmentioned above can be used for this purpose. The alkali metal compoundmay be used in an amount 1.2 to 2 times the mole of the phenol. In thereaction, the aforesaid polar solvent or the azeotropic solvent withwater may be employed. The bis-phenoxy compound is reacted with theacylating agent chlorobenzoyl chloride in the presence of aFriedel-Crafts reaction activator such as Lewis acid catalyst likealuminum chloride, boron trifluoride or zinc chloride. The chlorobenzoylchloride is used in an amount 2 to 4 times, preferably 2.2 to 3 timesthe moles of the bis-phenoxy compound. The Friedel-Crafts reactionactivator is used in an amount 1.1 to 2 times the moles of the activehalide compound such as the acylating agent chlorobenzoic acid. Thereaction time is in the range of 15 minutes to 10 hours, and thereaction temperature is in the range of −20 to 80° C. The solvent usedherein may be chlorobenzene, nitrobenzene or the like that is inactivein the Friedel-crafts reaction.

The compounds of Formula (E) in which r is 2 or greater may besynthesized by polymerization in accordance with the above-mentionedprocedure. In this case, a bisphenol such as2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane,2,2-bis(4-hydroxyphenyl)ketone or 2,2-bis(4-hydroxyphenyl) sulfone isconverted into an alkali metal salt of bisphenol and is subjected tosubstitution reaction with an excess of the activated aromatic halidesuch as 4,4-dichlorobenzophenone or bis(4-chlorophenyl)sulfone, in thepresence of a polar solvent such as N-methyl-2-pyrrolidone,N,N-dimethylacetamide or sulfolane.

Examples of such compounds include those represented by the followingformulae:

In the above formulae, p is 0 or a positive integer, generally up to100, and is preferably from 10 to 80.

To synthesize the polyarylene (C) having a sulfonate group, the monomer(D) and the oligomer (E) are reacted in the presence of a catalyst.

The catalyst used herein is a catalyst system containing a transitionmetal compound. This catalyst system essentially contains (1) atransition metal salt and a compound which functions as a ligand(referred to as the “ligand component” hereinafter), or a transitionmetal complex (including a copper salt) to which ligands arecoordinated, and (2) a reducing agent. A “salt” may be added to increasethe polymerization rate.

Examples of the transition metal salts include nickel compounds such asnickel chloride, nickel bromide, nickel iodide and nickelacetylacetonate; palladium compounds such as palladium chloride,palladium bromide and palladium iodide; iron compounds such as ironchloride, iron bromide and iron iodide; and cobalt compounds such ascobalt chloride, cobalt bromide and cobalt iodide. Of these, nickelchloride and nickel bromide are particularly preferred.

Examples of the ligand components include triphenylphosphine,2,2′-bipyridine, 1,5-cyclooctadiene and1,3-bis(diphenylphosphino)propane. Of these, triphenylphosphine and2,2′-bipyridine are preferred. The ligand components may be used singlyor in combination of two or more kinds.

Examples of the transition metal complexes with coordinated ligandsinclude nickel chloride-bis(triphenylphosphine), nickelbromide-bis(triphenylphosphine), nickel iodide-bis(triphenylphosphine),nickel nitrate-bis(triphenylphosphine), nickelchloride(2,2′-bipyridine), nickel bromide(2,2′-bipyridine), nickeliodide(2,2′-bipyridine), nickel nitrate(2,2′-bipyridine),bis(1,5-cyclooctadiene)nickel, tetrakis(triphenylphosphine)nickel,tetrakis(triphenylphosphito)nickel andtetrakis(triphenylphosphine)palladium. Of these, nickelchloride-bis(triphenylphosphine) and nickel chloride(2,2′-bipyridine)are preferred.

Examples of the reducing agents employable in the catalyst systeminclude iron, zinc, manganese, aluminum, magnesium, sodium and calcium.Of these, zinc, magnesium and manganese are preferable. These reducingagents may be used in a more activated form by being contacted with anacid such as an organic acid.

Examples of the “salts” employable in the catalyst system include sodiumcompounds such as sodium fluoride, sodium chloride, sodium bromide,sodium iodide and sodium sulfate; potassium compounds such as potassiumfluoride, potassium chloride, potassium bromide, potassium iodide andpotassium sulfate; and ammonium compounds such as tetraethylammoniumfluoride, tetraethylammonium chloride, tetraethylammonium bromide,tetraethylammonium iodide and tetraethylammonium sulfate. Of these,sodium bromide, sodium iodide, potassium bromide, tetraethylammoniumbromide and tetraethylammonium iodide are preferred.

The transition metal salt or the transition metal complex is usuallyused in an amount of 0.0001 to 10 mol, preferably 0.01 to 0.5 mol permol of the monomer and the oligomer combined (or simply the total of themonomers, (D)+(E), the same applies hereinafter). If the amount is lessthan 0.0001 mol, the polymerization may not proceed sufficiently. Theamount exceeding 10 mol may result in a lowered molecular weight.

When the catalyst system contains the transition metal salt and theligand component, the ligand component usually has an amount of 0.1 to100 mol, preferably 1 to 10 mol per mol of the transition metal salt. Ifthe amount is less than 0.1 mol, the catalytic activity may becomeinsufficient. The amount exceeding 100 mol may result in a loweredmolecular weight.

The amount of the reducing agent is usually in the range of 0.1 to 100mol, preferably 1 to 10 mol per mol of the total of the monomers. If thereducing agent is used in an amount less than 0.1 mol, thepolymerization may not proceed sufficiently. The amount thereofexceeding 100 mol may make purification of the resulting polymerdifficult.

When the “salt” is used, the amount thereof is usually 0.001 to 100 mol,preferably 0.01 to 1 mol per mol of the total of the monomers. If thesalt is used in an amount less than 0.001 mol, the effect of increasingthe polymerization rate is often insufficient. The amount thereofexceeding 100 mol may result in difficult purification of the resultingpolymer.

Suitable polymerization solvents for use in the reaction between themonomer (D) and the oligomer (E) include tetrahydrofuran, cyclohexanone,dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide,N-methyl-2-pyrrolidone, γ-butyrolactone andN,N′-dimethylimidazolidinone. Of these, tetrahydrofuran,N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone andN,N′-dimethylimidazolidinone are preferred. These polymerizationsolvents are desirably used after dried sufficiently.

The concentration of all the monomers combined in the polymerizationsolvent is usually in the range of 1 to 90% by weight, preferably 5 to40% by weight.

The polymerization temperature generally ranges from 0 to 200° C.,preferably from 50 to 120° C. The polymerization time is usually in therange of 0.5 to 100 hours, preferably 1 to 40 hours.

The polyarylene with a sulfonate group obtained using the monomer (D) issubjected to hydrolysis to convert the sulfonate group into the sulfonicacid group, thereby obtaining the polyarylene having a sulfonic acidgroup.

For example, the hydrolysis may be performed by any of the followingmethods:

(1) The polyarylene with a sulfonate group is added to an excess ofwater or an alcohol that contains a little hydrochloric acid, and themixture is stirred for at least 5 minutes.

(2) The polyarylene with a sulfonate group is reacted in trifluoroaceticacid at about 80 to 120° C. for about 5 to 10 hours.

(3) The polyarylene with a sulfonate group is reacted in a solution suchas N-methylpyrrolidone that contains lithium bromide in an amount 1 to 3times the moles of the sulfonate groups (—SO₃R) of the polyarylene, atabout 80 to 150° C. for about 3 to 10 hours, followed by addition ofhydrochloric acid.

Alternatively, the polyarylene having a sulfonic acid group may beobtained by copolymerizing a monomer having a skeleton similar to thatof the monomer (D) of Formula (D) except having no sulfonate groups withthe oligomer (E) of Formula (E), and sulfonating the thus-synthesizedpolyarylene copolymer. Specifically, a polyarylene having no sulfonicacid group is produced as described above and is treated with asulfonating agent to introduce the sulfonic acid group in thepolyarylene. The polyarylene having a sulfonic acid group may be thusobtained.

The sulfonation may be performed by treating the polyarylene having nosulfonic acid group with a sulfonating agent in the absence or presenceof a solvent by a common method, whereby the sulfonic acid group isintroduced in the polymer.

For introduction of the sulfonic acid groups, the polyarylene having nosulfonic acid group may be sulfonated with a known sulfonating agentsuch as sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid,sulfuric acid or sodium bisulfite, under known conditions.

-   Polymer Preprints, Japan, vol. 42, No. 3, p. 730 (1993)-   Polymer Preprints, Japan, vol. 43, No. 3, p. 736 (1994)-   Polymer Preprints, Japan, vol. 42, No. 7, pp. 2490-2492 (1993)

Specifically, the polyarylene having no sulfonic acid group is reactedwith the sulfonating agent in the absence or presence of a solvent. Thesolvents used herein include hydrocarbon solvents such as n-hexane;ether solvents such as tetrahydrofuran and dioxane; aprotic polarsolvents such as dimethylacetamide, dimethylformamide and dimethylsulfoxide; and halogenated hydrocarbons such as tetrachloroethane,dichloroethane, chloroform and methylene chloride. The reactiontemperature is not particularly limited, but is usually in the range of−50 to 200° C., preferably −10 to 100° C. The reaction time is usuallyfrom 0.5 to 1,000 hours, preferably from 1 to 200 hours.

The thus-produced polyarylene (C) having a sulfonic acid group willgenerally contain the sulfonic acid groups in an amount of 0.3 to 5meq/g, preferably 0.5 to 3 meq/g, more preferably 0.8 to 2.8 meq/g. Ifthe content of sulfonic acid groups is less than 0.3 meq/g, the protonconductivity will not reach a practical level. When it exceeds 5 meq/g,water resistance will be drastically deteriorated.

The content of sulfonic acid groups may be controlled by changing thetypes, amounts and combinations of the monomer (D) and the oligomer (E).

The polyarylene having a sulfonic acid group has a weight-averagemolecular weight in terms of polystyrene of 10,000 to 1,000,000,preferably 20,000 to 800,000, as measured by gel permeationchromatography (GPC).

The polyarylene having a sulfonic acid group may contain an anti-agingagent, preferably a hindered phenol compound with a molecular weight ofnot less than 500. Such anti-aging agents provide higher durability ofthe electrolyte.

The hindered phenol compounds employable in the invention includetriethylene

-   glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] (trade    name: IRGANOX 245),-   1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]    (trade name: IRGANOX 259),-   2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-3,5-triadine    (trade name: IRGANOX 565),-   pentaerythrithyl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]    (trade name: IRGANOX 1010),-   2,2-thio-diethylene-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)    propionate] (trade name: IRGANOX 1035),-   octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) (trade name:    IRGANOX 1076),-   N,N-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide) (trade    name: IRGANOX 1098),-   1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene    (trade name: IRGANOX 1330),-   tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate (trade name:    IRGANOX 3114) and-   3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyl    oxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane (trade    name: Sumilizer GA-80).

The hindered phenol compound may preferably be used in an amount of 0.01to 10 parts by weight based on 100 parts by weight of the polyarylenehaving a sulfonic acid group.

(Process for Producing Proton Conductive Membrane)

The proton conductive membrane according to the present invention may beproduced by dissolving the block copolymer in a casting solvent, andcasting the resulting composition on a substrate followed by drying.

In the invention, the casting solvent contains an organic solvent thatis not interactive with the ion conductive polymer segment (A).

Organic Solvent not Interactive with Ion Conductive Polymer Segment (A)

For use as the casting solvent for the production of the protonconductive membrane, the organic solvent not interactive with the ionconductive polymer segment (A) may be an organic solvent that does notcontain a nitrogen-containing substituent in which the nitrogen atom isbonded by a single bond or a double bond. (Namely, the organic solventis not an amine compound, amide compound, imide compound, diazo compoundor the like.)

Examples of such solvents include methanol (pδ14.28), ethanol (δ 12.92),1-propanol (δ 11.07), 2-propanol (δ 11.50), n-butyl alcohol (δ 11.30),2-methyl-1-propanol (δ 11.11*), 1-pentanol (δ 10.96*), 2-pentanol (δ10.77*), 3-pentanol (δ 10.77*), 2-methyl-1-butanol (δ 10.77*),3-methyl-1-butanol (δ 10.77*), 2-methyl-2-butanol (δ 10.58*),3-methyl-2-butanol (δ 10.58*), 2,2-dimethyl-1-propanol (δ 10.58*),cyclohexanol (δ 12.44*), dicyclohexanol (δ 10.95), 1-hexanol (δ 10.68*),2-methyl-1-pentanol (δ 10.51*), 2-methyl-2-pentanol (δ 10.34*),4-methyl-2-pentanol (δ 10.34*), 2-ethyl-1-butanol (δ 10.51*),1-methylcyclohexanol (δ 11.76*), 2-methylcyclohexanol (δ 11.74*),3-methylcyclohexanol (δ 11.74*), 4-methylcyclohexanol (δ 11.74*),1-octanol (δ 10.28*), 2-octanol (δ 10.14*), 2-ethyl-1-hexanol (δ10.14*), ethylene glycol (δ 16.30), propylene glycol (δ 14.80),1,3-butanediol (δ 14.14), glycerol (δ 21.10), m-cresol (δ 11.11),diethylene glycol (δ 14.60), dipropylene glycol (δ 15.52), ethyl lactate(δ 10.57), n-butyl lactate (δ 9.68), diacetone alcohol (δ 10.18),dioxane (δ 10.0), butyl ether (δ 7.78*), phenyl ether (bp. 187° C., δ12.16), isopentyl ether (δ 7.63*), dimethoxyethane (δ 7.63*),diethoxyethane (δ 7.85*), bis(2-methoxyethyl)ether (δ 8.10*),bis(2-ethoxyethyl)ether (δ 8.19*), cineol (δ 8.97*), benzyl ethylether(δ 9.20*), furan (δ 9.09), tetrahydrofuran (δ 9.52), anisole (δ 9.38*),phenetole (δ 9.27*), acetal (δ 7.65*), acetone δ 9.77), methyl ethylketone (δ 9.27), 2-pentanone (δ 8.30*), 3-pentanone (δ 8.30*),cyclopentanone (δ 12.81*), cyclohexanone (δ 9.88), 2-hexanone (δ 8.84*),4-methyl-2-pentanone (δ 8.68*), 2-heptanone (δ 8.84*),2,4-dimethyl-3-pentanone (δ 8.49), 2-octanone (δ 8.81*), acetophenone (δ9.68), mesityl oxide (δ 9.20), benzaldehyde (δ 10.40), ethyl acetate (δ9.10), n-butyl acetate (δ 8.46), isobutyl acetate (δ 8.42), sec-butylacetate (δ 8.51*), isoamyl acetate (δ 8.32), pentyl acetate (δ 8.69*),isopentyl acetate (δ 8.52*), 3-methoxybutyl acetate (δ 8.52*), methylbutyrate (δ 8.72*), ethyl butyrate (δ 8.70*), methyl lactate (bp. 145°C., δ 12.42*), ethyl lactate (bp. 155° C., δ 10.57), butyl lactate (δ11.26*), γ-butyrolactone (δ 12.78), 2-methoxyethanol (δ 11.98*),2-ethoxyethanol (δ 11.47*), 2-(methoxymethoxy)ethanol (δ 11.60*),2-isopropoxyethanol (δ 10.92*), 1-methoxy-2-propanol (δ 11.27*),1-ethoxy-2-propanol (δ 10.92*), dimethyldiethylene glycol (δ 9.41),dimethyl sulfoxide (bp. 189° C., δ 12.93), dimethyl sulfone (δ 14.59),diethyl sulfide (δ 8.46), acetonitrile (δ 11.9), butyronitrile (δ 9.96),nitromethane (δ 12.30), nitroethane (δ 11.09), 2-nitropropane (δ 10.02),nitrobenzene (δ 10.62), benzene (δ 9.15), toluene (δ 8.91), xylene (δ8.80), hexane (δ 7.24) and cyclohexane (δ 8.18).

These organic solvents may be used singly, or they may be used incombination, in which case preferably at least one of the solventscontains at least one group selected from —O—, —OH, —CO—, —SO₂—, —SO₃—,—CN and —COOR (where R is a hydrogen atom, a hydrocarbon group or asalt)

The organic solvent not interactive with the ion conductive polymersegment (A) desirably accounts for not less than 30% by weight,preferably not less than 60% by weight, more preferably not less than90% by weight of the total solvent. This amount of the solvent reducesthe influence of an organic solvent that interacts with the ionconductive polymer segment (A), and leads to a morphology of themembrane in which the ion conductive polymer segment (A) forms acontinuous phase, whereby the ion conductive groups in the segment (A)are arranged uniformly through the membrane and can adsorb and bindthereto increased amounts of water, and consequently water is preventedfrom drying at low humidities and from freezing at low temperatures andthe proton conductive membrane can achieve sufficient protonconductivity even at low humidities and low temperatures.

When the amount of the solvent is less than described above, an organicsolvent that interacts with the ion conductive polymer segment (A) has agreater influence, and the membrane tends to have a morphology in whichthe ion conductive polymer segment (A) forms a non-continuous phase,whereby the ion conductive groups in the segment (A) are not arrangeduniformly through the membrane and adsorb and bind thereto reducedamounts of water, and consequently the proton conductive membrane failsto achieve sufficient proton conductivity at low humidities and lowtemperatures.

In the above examples, the values indicated with a delta 6 are thesolubility parameters ((cal/mol)^(1/2)), and those followed by thesymbol * are the values calculated by the Fedors method (R. F. Fedors,Polym. Eng. Sci., 14 [2] 147 (1974)).

One or more organic solvents not interactive with the ion conductivepolymer segment (A) may be used, and the average solubility parameter ispreferably in the range of 8.5 to 16 (cal/mol)^(1/2), more preferably10.0 to 14.0 (cal/mol)^(1/2). When the average solubility parameter isoutside this range, the solution viscosity is so high that the filmproduction is difficult and the surface smoothness is often poor. Theaverage solubility parameter is calculated by the following formula:δ_(Ave.)=δ₁ xA ₁/100+δ₂ xA ₂/100+ . . . +δ_(n) xA _(n)/100wherein:

δ_(Ave.): average solubility parameter

δ_(n): solubility parameter of each solvent

A_(n): % by weight of each solvent relative to the organic solvents notinteractive with the ion conductive polymer segment (A)

Examples of the organic solvents interactive with the ion conductivepolymer segment (A) include basic organic solvents such as pyridine (δ10.61), n-methyl-2-pyrrolidone (δ 11.17), 2-pyrrolidone (δ 13.88),dimethylacetamide (δ 11.12), tetramethylurea (δ 10.60) anddimethylformamide (δ 12.14). The amount of these solvents should be lessthan 30% (by volume) of the total solvent.

Composition

The composition for producing the proton conductive membrane includesthe block copolymer and the organic solvent.

As described above, the organic solvent preferably contains not lessthan 30% (by volume relative to the total organic solvent) of theorganic solvent not interactive with the ion conductive polymer segment(A).

In addition to the above components, the composition may containinorganic acids such as sulfuric and phosphoric acids, organic acidsincluding carboxylic acids, an appropriate amount of water, and thelike.

Although the polymer concentration depends on the molecular weight ofthe block copolymer, it is generally from 5 to 40% by weight, preferablyfrom 7 to 25% by weight. The polymer concentration less than 5% byweight causes difficulties in producing the membrane in large thicknessand results in easy occurrence of pinholes. On the other hand, when thepolymer concentration exceeds 40% by weight, the solution viscositybecomes so high that the film production is difficult and the surfacesmoothness is often poor.

The solution viscosity of the composition may vary depending on the typeof the block copolymer and the polymer concentration. Generally, itranges from 2,000 to 100,000 mPa·s, preferably from 3,000 to 50,000mPa·s. When the viscosity is less than 2,000 mPa·s, the solution willhave too high a fluidity and may spill out of the substrate during themembrane production. The viscosity exceeding 100,000 mPa·s is so highthat the solution cannot be extruded through a die and the film-castingis difficult.

The composition for producing the proton conductive membrane may beprepared by mixing the aforesaid components in a predetermined ratio byconventional methods, for example by mixing with a mixer such as a waverotor, a homogenizer, a disperser, a paint conditioner or a ball mill.

Production of Proton Conductive Membrane

The proton conductive membrane according to the invention may beproduced by casting the composition on a substrate, followed by drying.

Specifically, the composition is cast over a substrate to form a film.

The substrate used herein may be a polyethyleneterephthalate (PET) film,but is not limited thereto. Any substrates commonly used in the solutioncasting methods may be employed. Examples include, but not particularlylimited to, plastic substrates and metal substrates.

The film produced by the casting method is dried at 30 to 160° C.,preferably 50 to 150° C., for 3 to 180 minutes, preferably 5 to 120minutes. The dry thickness is generally from 10 to 100 μm, preferably 20to 80 μm. When the solvent remains in the membrane after the drying, itmay be removed by extraction with water as required.

The proton conductive membrane may be used as electrolytes for primaryand secondary batteries, as proton conductive membranes for displayelements, sensors, signaling media and solid condensers, and as ionexchange membranes.

In particular, (i) the membrane has a morphology including a microphaseseparated structure and (ii) the ion conductive polymer segment (A)forms a continuous phase, whereby the ion conductive groups in thesegment (A) are arranged uniformly through the membrane and can adsorband bind thereto increased amounts of water, and consequently water isprevented from drying at low humidities and from freezing at lowtemperatures and the membrane can achieve sufficient proton conductivityeven at low humidities and low temperatures. Thus, the proton conductivemembrane of the invention is suitable for use in hydrogen powered fuelcells for vehicles.

EXAMPLES

The present invention will be hereinafter described in greater detail byExamples presented below, but it should be construed that the inventionis in no way limited to those Examples.

In Examples, the sulfonic acid equivalent, molecular weight, watercontent, and proton conductivity were determined as described below.

1. Sulfonic Acid Equivalent

The polymer having a sulfonic acid group was washed until the washingsbecame neutral, and free residual acids were removed. The polymer wassufficiently washed with water and dried. A predetermined amount of thepolymer was weighed out and dissolved in a THF/water mixed solvent. Theresultant solution was mixed with phenolphthalein as an indicator, andthe mixture was titrated with a NaOH standard solution to obtain a pointof neutralization, from which the sulfonic acid equivalent wasdetermined.

2. Measurement of Molecular Weight

The polyarylene having no sulfonic acid group was analyzed by GPC usingtetrahydrofuran (THF) as a solvent to determine the weight-averagemolecular weight in terms of polystyrene. The polyarylene having asulfonic acid group was analyzed by GPC using an eluting solutionconsisted of N-methyl-2-pyrrolidone (NMP) mixed with solvents lithiumbromide and phosphoric acid, to determine the molecular weight in termsof polystyrene.

3. Measurement of Water Content in Membrane

The proton conductive membrane film was cut to 2 cm×3 cm, and wasmeasured for initial weight. The film and water were placed in a Teflon™bottle, and the film was soaked at 120° C. for 24 hours using a pressurecooker tester (HIRAYAMA MANUFACTURING CORPORATION). The film was takenout, and the water droplets on the surface were towel dried. The filmwas weighed to determine the water content in the membrane (%).Water content in membrane (%)=(Soaked film weight (g)−Initial weight(g))/Initial weight (g)×1004. Measurement of Proton Conductivity

A 5 mm wide strip specimen of the proton conductive membrane, holdingfive platinum wires (φ=0.5 mm) at intervals of 5 mm on its surface, wasplaced in a thermo-hygrostat. The alternating current impedance betweenthe platinum wires was measured at 10 kHz under the conditions of 85° C.and 45% RH and under the conditions of temperatures of 25° C., 5° C., 0°C., −10° C. and −20° C. and 50% RH. This measurement was carried outusing a chemical impedance measuring system (NF Corporation) andthermo-hygrostat JW241 (Yamato Science Co., Ltd.). The alternatingcurrent resistance was measured in each case where the interwiredistance was changed from 5 mm to 20 mm among the five platinum wires.The resistivity of the membrane was calculated from a gradient betweenthe interwire distance and the resistance. The reciprocal number ofresistivity was obtained as alternating current impedance, from whichthe proton conductivity was calculated.Resistivity R (Ω·cm)=0.5 (cm)×membrane thickness(cm)×resistance/interwire distance gradient (Ω/cm)

Synthetic Example 1

(Preparation of Oligomer)

A 1-L three-necked flask equipped with a stirrer, a thermometer, acooling tube, a Dean-Stark tube and a three-way nitrogen inlet tube, wascharged with 67.3 g (0.20 mol) of2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (bisphenol AF),60.3 g (0.24 mol) of 4,4′-dichlorobenzophenone (4,4′-DCBP), 71.9 g (0.52mol) of potassium carbonate, 300 ml of N,N-dimethylacetamide (DMAc) and150 ml of toluene. With the flask in an oil bath, the materials werereacted by being stirred in a nitrogen atmosphere at 130° C. Thereaction was carried out while water resulting from the reaction wasformed into an azeotropic mixture with toluene and was removed outsidethe system through the Dean-Stark tube. Water almost ceased to occurafter about 3 hours, and most of the toluene was removed while graduallyraising the reaction temperature from 130° C. to 150° C. The reactionwas continuously performed at 150° C. for 10 hours, and 10.0 g (0.040mol) of 4,4′-DCBP was added to carry out the reaction for another 5hours. The reaction liquid was cooled naturally and was filtered toremove precipitated by-product inorganic compounds. The filtrate waspoured into 4 L of methanol to precipitate the product. The precipitatedproduct was filtered off, dried and dissolved in 300 ml oftetrahydrofuran. The resultant solution was poured into 4 L of methanolto perform reprecipitation. Consequently, 95 g of an objective compoundwas obtained (85% yield).

GPC (THF solvent) showed that the polymer had a weight-average molecularweight of 11,200 in terms of polystyrene. The polymer was found to besoluble in THF, NMP, DMAc and sulfolane, and to have Tg of 110° C. and athermal decomposition temperature of 498° C.

The compound obtained was identified to be an oligomer represented byFormula (I) (hereinafter, the BCPAF oligomer)

Synthetic Example 2 Preparation of neopentyl-protected polyarylenecopolymer

A 1-L three-necked flask equipped with a stirrer, a thermometer, acooling tube, a Dean-Stark tube and a three-way nitrogen inlet tube, wascharged, in a nitrogen atmosphere, with 39.58 g (98.64 mmol) ofneo-pentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate, 15.23 g (1.36 mmol)of the BCPAF oligomer (Mn=11,200) obtained in Synthetic Example 1, 1.67g (2.55 mmol) of Ni(PPh₃)₂Cl₂, 10.49 g (40 mmol) of PPh₃, 0.45 g (3mmol) of NaI, 15.69 g (240 mmol) of zinc powder and 390 ml of dry NMP.The reaction system was heated (finally to 75° C.) with stirring toperform reaction for 3 hours. The polymerization solution was dilutedwith 250 ml of THF, stirred for 30 minutes, and filtered with use ofCelite as a filter aid. The filtrate was poured into large excess (1500ml) of methanol to precipitate the product. The precipitated product wasfiltered off, air dried, redissolved in THF/NMP (200/300 ml) andprecipitated in large excess (1500 ml) of methanol. The precipitatedproduct was air dried and then heat dried to give 47.0 g (99% yield) ofan objective yellow fibrous copolymer including a neopentyl-protectedsulfonic acid derivative. GPC resulted in Mn of 47,600 and Mw of159,000.

A 5.1 g portion of the copolymer was dissolved in 60 ml of NMP, followedby heating to 90° C. To the reaction system, a mixture consisting of 50ml of methanol and 8 ml of concentrated hydrochloric acid was added allat once. Reaction was carried out under mild reflux conditions for 10hours while maintaining a suspension state. Excess methanol wasevaporated using a distillation apparatus equipped, and a light greentransparent solution resulted. The solution was poured into an excess ofwater/methanol (1:1 by weight) to precipitate the polymer. The polymerwas washed with ion exchange water until the pH of the washings becamenot less than 6. IR spectroscopy and quantitative analysis for ionexchange capacity showed that the sulfonate groups (—SO₃R^(a)) had beenquantitatively converted to the sulfonic acid groups (—SO₃H). Thepolymer had a structure represented by Formula (II) below.

GPC for the polyarylene copolymer having a sulfonic acid group resultedin Mn of 53,200 and Mw of 185,000. The sulfonic acid equivalent was 1.9meq/g.

Synthetic Example 3

(1) Synthesis of Oligomer

A 1-L three-necked flask equipped with a stirrer, a thermometer, aDean-Stark tube, a nitrogen inlet tube and a cooling tube, was chargedwith 48.8 g (284 mmol) of 2,6-dichlorobenzonitrile, 89.5 g (266 mmol) of2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and 47.8 g (346mmol) of potassium carbonate. After the flask had been purged withnitrogen, 346 ml of sulfolane and 173 ml of toluene were added, followedby stirring. The reaction liquid was heated at 150° C. under reflux inan oil bath. Water resulting from the reaction was trapped in theDean-Stark tube. Water almost ceased to occur after 3 hours, and thetoluene was removed outside the reaction system through the Dean-Starktube. The reaction temperature was slowly raised to 200° C. and stirringwas performed for 3 hours. Thereafter, 9.2 g (53 mmol) of2,6-dichlorobenzonitrile was added to carry out the reaction for another5 hours.

The reaction liquid was cooled naturally, diluted with 100 ml oftoluene, and filtered to remove insoluble inorganic salts. The filtratewas poured into 2 L of methanol to precipitate the product. Theprecipitated product was filtered off, dried and dissolved in 250 ml oftetrahydrofuran. The resultant solution was poured into 2 L of methanolto perform reprecipitation. The precipitated white powder was filteredoff and dried to yield 109 g of an objective product. GPC resulted in anumber-average molecular weight (Mn) of 9,500.

The compound obtained was identified to be an oligomer represented byFormula (III):

Synthetic Example 4

Synthesis of Sulfonated Polyarylene

A 1-L three-necked flask equipped with a stirrer, a thermometer and anitrogen inlet tube was charged with 135.2 g (337 mmol) of neopentyl3-(2,5-dichlorobenzoyl) benzenesulfonate, 48.7 g (5.1 mmol) of theoligomer of Formula (III) obtained in Synthetic Example 3 (Mn=9,500),6.71 g (10.3 mmol) of bis(triphenylphosphine)nickel dichloride, 1.54 g(10.3 mmol) of sodium iodide, 35.9 g (137 mmol) of triphenylphosphine,and 53.7 g (821 mmol) of zinc. The flask was purged with dry nitrogen,and 430 ml of N,N-dimethylacetamide (DMAc) was added. The mixture wasstirred for 3 hours while maintaining the reaction temperature at 80° C.The reaction liquid was diluted with 730 ml of DMAc, and insolubles werefiltered out.

The solution obtained was introduced into a 2-L three-necked flaskequipped with a stirrer, a thermometer and a nitrogen inlet tube, andwas heated to 115° C. with stirring. Subsequently, 44 g (506 mmol) oflithium bromide was added. The mixture was stirred for 7 hours and waspoured into 5 L of acetone to precipitate the product. The product waswashed sequentially with 1N hydrochloric acid and pure water, and wasdried to give 122 g of an objective polymer. The weight-averagemolecular weight (Mw) of the polymer was 135,000. The polymer obtainedwas assumed to be a sulfonated polymer represented by Formula (IV). Theion exchange capacity of the polymer was 2.3 meq/g.

Example 1

A 50-cc screw cap tube was charged with 4 g of the sulfonicacid-containing polyarylene obtained in Synthetic Example 2, 11.7 g of1-methoxy-2-propanol and 17.6 g of γ-butyrolactone, followed by stirringwith a wave rotor for 24 hours. Consequently, a uniform polymer solutionhaving a viscosity of 5,000 cp resulted.

The solution was cast on a PET film using a bar coater, and the coatingwas dried at 80° C. for 30 minutes and at 120° C. for 60 minutes to givea uniform and transparent solid electrolyte film A having a thickness of40 μm. For observation of the internal structure of the film, anultrathin piece was cut out from the film and was stained with leadnitrate. The piece was observed with transmission electron microscope(hereinafter TEM) HF-100FA manufactured by Hitachi, Ltd.

The TEM observation showed an isotropic microphase separated structureformed by domains of the polymer segments (A) with ion conductive groupsand domains of the polymer segments (B) without ion conductive groups.(See FIG. 1.)

In the co-continuous structure shown in FIG. 1, the domains of thesegments (B) formed non-continuous domains, and the domains of thesegments (A) constituted matrixes and linked together to form acontinuous network through the membrane. Analysis of the TEM picturewith an image processing software (scion image) resulted in a longperiod of 23 nm.

The film obtained was evaluated for water content and protonconductivity by the above methods. The results are given in Tables 1 and2.

Example 2

A 50-cc screw cap tube was charged with 4 g of the sulfonicacid-containing polyarylene obtained in Synthetic Example 2, 11.7 g of1-methoxy-2-propanol, 8.8 g of toluene and 8.8 g of γ-butyrolactone,followed by stirring with a wave rotor for 24 hours. Consequently, auniform polymer solution having a viscosity of 4,500 cp resulted.

The solution was cast on a PET film using a bar coater, and the coatingwas dried at 80° C. for 30 minutes and at 120° C. for 60 minutes to givea uniform and transparent solid electrolyte film B having a thickness of38 μm. For observation of the internal structure of the film, anultrathin piece was cut out from the film and was stained with leadnitrate. The piece was observed with transmission electron microscope(hereinafter TEM) HF-100FA manufactured by Hitachi, Ltd.

The TEM observation showed an isotropic microphase separated structureformed by domains of the polymer segments (A) with ion conductive groupsand domains of the polymer segments (B) without ion conductive groups.The microphase separated structure was clearer than that of Example 1,and the domains of the segments (B) formed non-continuous domainssimilar to dispersed phases, and the domains of the segments (A)constituted matrixes and linked together to form a continuous networkthrough the membrane. Analysis of the TEM picture with an imageprocessing software (scion image) resulted in a long period of 25 nm.

The film obtained was evaluated for water content and protonconductivity by the above methods. The results are given in Tables 1 and2.

Example 3

A 50-cc screw cap tube was charged with 4 g of the sulfonicacid-containing polyarylene obtained in Synthetic Example 4, 14.4 g of1-methoxy-2-propanol and 21.6 g of γ-butyrolactone, followed by stirringwith a wave rotor for 24 hours. Consequently, a uniform polymer solutionhaving a viscosity of 7,000 cp resulted.

The solution was cast on a PET film using a bar coater, and the coatingwas dried at 80° C. for 30 minutes and at 120° C. for 60 minutes to givea uniform and transparent solid electrolyte film A having a thickness of40 μm. For observation of the internal structure of the film, anultrathin piece was cut out from the film and was stained with leadnitrate. The piece was observed with transmission electron microscope(hereinafter TEM) HF-100FA manufactured by Hitachi, Ltd.

The TEM observation showed an isotropic microphase separated structureformed by domains of the polymer segments (A) with ion conductive groupsand domains of the polymer segments (B) without ion conductive groups.

In the co-continuous structure, the domains of the segments (B) formednon-continuous domains, and the domains of the segments (A) constitutedmatrixes and linked together to form a continuous network through themembrane. Analysis of the TEM picture with an image processing software(scion image) resulted in a long period of 20 nm.

The film obtained was evaluated for water content and protonconductivity by the above methods. The results are given in Tables.

Comparative Example 1

A 50-cc screw cap tube was charged with 4 g of the sulfonicacid-containing polyarylene obtained in Synthetic Example 2 and 29.3 gof N-methyl-2-pyrrolidone, followed by stirring with a wave rotor for 24hours. Consequently, a uniform polymer solution having a viscosity of4,000 cp resulted.

The solution was cast on a PET film using a bar coater, and the coatingwas dried at 80° C. for 30 minutes and at 140° C. for 60 minutes to givea uniform and transparent solid electrolyte film C having a thickness of40-m. For observation of the internal structure of the film, anultrathin piece was cut out from the film and was stained with leadnitrate. The piece was observed with transmission electron microscope(hereinafter TEM) HF-100FA manufactured by Hitachi, Ltd.

The TEM observation showed an isotropic microphase separated structureformed by domains of the polymer segments (A) with ion conductive groupsand domains of the polymer segments (B) without ion conductive groups.To the contrary of the co-continuous structure shown in FIG. 1, thedomains of the segments (B) formed more non-continuous domains, and thedomains of the segments (A) linked together to form a continuous networkthrough the membrane. Analysis of the TEM picture with an imageprocessing software (scion image) resulted in a long period of 30 nm.

The film obtained was evaluated for water content and protonconductivity by the above methods. The results are given in Tables.

Comparative Example 2

A 50-cc screw cap tube was charged with 4 g of the sulfonicacid-containing polyarylene obtained in Synthetic Example 2, 2.9 g ofwater, 21.7 g of dimethoxyethane and 4.7 g of 2-propanol, followed bystirring with a wave rotor for 24 hours. Consequently, a uniform polymersolution having a viscosity of 11,000 cp resulted.

The solution was cast on a PET film using a bar coater, and the coatingwas dried at 80° C. for 30 minutes and at 120° C. for 60 minutes to givea uniform and transparent solid electrolyte film D having a thickness of39 μm. For observation of the internal structure of the film, anultrathin piece was cut out from the film and was stained with leadnitrate. The piece was observed with transmission electron microscope(hereinafter TEM) HF-100FA manufactured by Hitachi, Ltd.

The TEM observation showed a disordered structure without microphaseseparation of domains of the polymer segments (A) with ion conductivegroups and domains of the polymer segments (B) without ion conductivegroups.

The solid electrolyte film D was broken during the water contentmeasurement, proving bad resistance to hot water. The measurement ofproton conductivity was canceled.

TABLE 1 Water content (%) (120° C. Polymer Weight ratio of solvents (%)water × 24 hr) Ex. 1 Syn. Ex. 2 1-methoxy-2-propanol/γ- 200butyrolactone (40/60) Ex. 2 Syn. Ex. 2 1-methoxy-2- 240propanol/toluene/γ- butyrolactone (40/30/30) Ex. 3 Syn. Ex. 41-methoxy-2-propanol/γ- 130 butyrolactone (40/60) Comp. Syn. Ex. 2N-methyl-2-pyrrolidone 170 Ex. 1 (100) Comp. Syn. Ex. 2Water/dimethoxyethane/2- Broken Ex. 2 propanol (10/74/16) membrane

TABLE 2 Conductivity (Ω · cm) 85° C./45% 25° C./50% 5° C./50% 0° C./50%−10° C./50% −20° C./50% Ex. 1 2.3 × 10⁻² 1.6 × 10⁻² 8.7 × 10⁻³ 8.9 ×10⁻³ 5.3 × 10⁻³ 3.5 × 10⁻³ Ex. 2 2.5 × 10⁻² 1.7 × 10⁻² 8.9 × 10⁻³ 9.1 ×10⁻³ 5.6 × 10⁻³ 3.8 × 10⁻³ Ex. 3 2.7 × 10⁻² 1.8 × 10⁻² 8.9 × 10⁻³ 9.2 ×10⁻³ 6.0 × 10⁻³ 4.1 × 10⁻³ Comp. Ex. 1 1.7 × 10⁻² 1.2 × 10⁻² 6.1 × 10⁻³5.4 × 10⁻³ 2.6 × 10⁻³ 1.6 × 10⁻³ Comp. Ex. 2 Canceled Canceled CanceledCanceled Canceled Canceled

1. A proton conductive membrane comprising: a blockpolyarylene-copolymer comprising an ion conductive polymer segment (A)and an ion nonconductive polymer segment (B), the segment (A) and thesegment (B) being covalently bound in a manner such that main chainskeletons of the segments are covalently bound at aromatic rings thereofthrough binding groups, (i) the membrane having a morphology comprisinga microphase separated structure, (ii) the ion conductive polymersegment (A) forming a continuous phase, wherein the blockpolyarylene-copolymer has a structure in which main chain skeletons ofthe copolymer are covalently bound at aromatic rings thereof throughbinding groups.
 2. The proton conductive membrane according to claim 1,wherein the block polyarylene-copolymer comprises the polymer segments(A) and (B) that comprise repeating structural units represented byFormulae (A) and (B), respectively:

wherein Y is a divalent electron-withdrawing group; Z is a divalentelectron-donating group or a direct bond; Ar is an aromatic group havinga substituent —SO₃H; m is an integer ranging from 0 to 10; n is aninteger ranging from 0 to 10; and k is an integer ranging from 1 to 4;

wherein A and D are each a direct bond or at least one structureselected from the group consisting of —CO—, —SO₂—, —SO—, —CONH—, —COO—,—(CF₂)₁— (wherein 1 is an integer ranging from 1 to 10), —(CH₂)₁—(wherein 1 is an integer ranging from 1 to 10), —C(R′)₂— (wherein R′ isan alkyl group, a fluoroalkyl group or an aryl group), —O—, —S—,cyclohexylidene group and fluorenylidene group; B's are each an oxygenor a sulfur atom; R¹ to R¹⁶ are the same or different from one anotherand are each at least one atom or group selected from the groupconsisting of a hydrogen atom, a fluorine atom, alkyl groups, partiallyor fully halogenated alkyl groups, allyl groups, aryl groups, nitrogroup and nitrile group; s and t are the same or different and are eachan integer ranging from 0 to 4; and r is an integer of 0 or 1 orgreater.
 3. The proton conductive membrane according to claim 1 or 2,wherein the ion conductive polymer segment has a sulfonic acid group. 4.A process for producing a proton conductive membrane as described claim1, which process comprises dissolving a block polyarylene-copolymer in acasting solvent to form a solution, wherein the blockpolyarylene-copolymer comprises an ion conductive polymer segment (A)and an ion nonconductive polymer segment (B) that are covalently boundto each other, casting the solution over a substrate, and drying,wherein the casting solvent comprises at least 30% by weight of anorganic solvent that is not interactive with the ion conductive polymersegment (A).
 5. The process for producing a proton conductive membraneaccording to claim 4, wherein the organic solvent that is notinteractive with the ion conductive polymer segment (A) (i) does notcomprise a nitrogen comprising substituent in which the nitrogen atom isbonded by a single bond or a double bond, and (ii) comprises at leastone group selected from the group consisting of —O—, —OH, —CO—, —SO₂—,—SO₃—, —CN, and —COOR; wherein R is a hydrogen atom, a hydrocarbon groupor a salt.
 6. The proton conductive membrane of claim 2, wherein inFormula (A), Z is a direct bond.
 7. The proton conductive membrane ofclaim 2, wherein in Formula (A), Z is a divalent electron-donatinggroup.
 8. The proton conductive membrane of claim 7, wherein divalentelectron-donating group Z in Formula (A) is selected from the groupconsisting of —(CH₂)—, —C(CH₃)₂—, —O—, —S—, —CH═CH—, —C≡C—,


9. The proton conductive membrane of claim 2, wherein Ar, in thearomatic group Ar having a substituent —SO₃H, in Formula (A), isselected from the group consisting of phenyl, naphthyl, anthracenyl, andphenanthyl.
 10. The proton conductive membrane of claim 9, wherein Ar isphenyl.
 11. The proton conductive membrane of claim 9, wherein Ar isnaphthyl.
 12. The proton conductive membrane of claim 2, wherein in theFormula (B), A and D are each a direct bond.
 13. The process of claim 5,wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —O—.
 14. The process of claim5, wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —OH.
 15. The process of claim5, wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —CO—.
 16. The process of claim5, wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —SO₂—.
 17. The process of claim5, wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —CN.
 18. The process of claim5, wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —COOR, wherein R is a hydrogenatom.
 19. The process of claim 5, wherein the organic solvent that isnot interactive with the ion conductive polymer segment (A) comprises—COOR, wherein R is a hydrocarbon group.
 20. The process of claim 5,wherein the organic solvent that is not interactive with the ionconductive polymer segment (A) comprises —COOR, wherein R is a hydrogenatom, a hydrocarbon group or a salt.